All living organisms that inhabit our planet are characterized by certain criteria. First of all, it is the activity and the course of various physiological processes. Otherwise, their manifestation can be defined by such a concept as life activity. This is the totality of all processes that occur in living beings, regardless of the level of their organization. In this article we will dwell in detail on some of them.
Vital activity is the basis of the existence of organisms
The mechanisms of physiological processes and their level are determined by the peculiarities of the structure of various organisms. For example, human life is very complex and subject to nervous and humoral regulation. And in viruses, it comes down to a primitive process of reproduction by self-assembly. Photosynthesis of plants, digestion of animals, division of bacterial cells - is nothing but life. This is a combination of processes that provide for the exchange of substances and homeostasis.
Living organisms are characterized by such processes as nutrition, respiration, movement, reproduction, growth, development, heredity, variability and adaptation. Life activity is a combination of all of the above. Each systematic group has its own characteristics. Let's look at some of them in more detail.
Depending on the type of food, all organisms are divided into auto- and heterotrophs. The first group includes plants and some types of bacteria. They are able to produce organic substances on their own. For this, plants use solar energy, due to which glucose monosaccharide is synthesized in chloroplasts. Therefore, they are also called phototrophs. Bacteria are a source of nutrition is the energy of chemical bonds of organic compounds. Such unicellular organisms are also called hemotrophs.
Animals and fungi absorb only ready-made organic substances. They are heterotrophs. Among them, several groups are distinguished, which differ in the nature of the food source. For example, predators attack their prey and kill it, and saprotrophs consume the decomposing organic. To a special group are mixotrophs. In the presence of favorable conditions, they synthesize carbohydrates independently, and if necessary switch to heterotrophic nutrition. Examples of mixotrophs are euglena green, mistletoe, rogolist, wolvox.
The concept of breathing includes not only the absorption of oxygen and the release of carbon dioxide. During this process, oxidation of organic substances takes place with the release of a certain amount of energy. It is "stored" in ATP molecules. As a result, organisms are provided with a reserve, which, if necessary, can be used. In plants, respiration occurs in the mitochondria of cells, and gas exchange provides such elements of the integumentary tissue as stomata and lenticles. In animals, the organs that provide this process are gills or lungs.
Many prokaryotic organisms are capable of anaerobic respiration. This means that the oxidation of organic substances in them occurs without the participation of oxygen. These include nitrogen-fixing, iron and sulfur bacteria.
Another manifestation of life is the reproduction of organisms. This process ensures the continuity of generations. Important properties of all living things are the ability to transmit characteristics by inheritance and acquire new ones, which guarantees their adaptation to the constantly changing environmental conditions.
There are two main ways of reproduction: sexual and asexual. The first occurs with gametes. Female and male sex cells merge, giving rise to a new organism. Paroxysmal reproduction can occur by dividing the cells in two, sporulation, budding or vegetatively.
Growth and development
The conditions of life of any organisms are also included in the quantitative and qualitative transformations that occur during their ontogeny. Due to cell division and regeneration processes, growth is provided. In plants and mushrooms it is unlimited. This means that they increase in size throughout life. Animals, however, grow only a certain period. After that, this process is terminated. Growth is accompanied by development. This concept is a qualitative change, which manifests itself in the form of complicating life processes. Growth and development accompany each other and are inextricably linked.
So, the vital activity of organisms is a combination of physiological processes aimed at ensuring metabolism and homeostasis - maintaining the constancy of the internal environment. The main ones are nutrition, breathing, reproduction, movement, growth and development.